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Abstract

Gas lift is a widespread method of artificial lift. However, on wells where there is no provision for Side Pocket Mandrels one way to avoid a heavy work over, is to run a macaroni string inside the existing tubing ; gas can be injected via the macaroni and the lifted fluid flowed through the tubing-macaroni annulus.

On offshore wells, regulations or Company policy may impose the use of Surface Controlled Subsurface Safety Valve. This paper describes a new type of SC-SSV, run as an integral part of the macaroni string, which will close the macaroni string and the tubing-macaroni annulus. Associated equipment to set the SC-SSV in place and to seal the macaroni string system in the Chrismas-tree is also covered in the paper. In addition, field experience on over 30 offshore wells equipped with such a system is related.

Introduction

The major Indonesia offshore oil fields of Handil and Bekapal have been operated by TOTAL Indonesie since 1973. As a result of the large number of reservoirs, (250 different zones were classified), wells are completed with a dual string tubing 3 1/2 × 3 1/2.

Early standard dual completions did not have any facilities for future artificial lift development; as gas reservoirs were available, gas lift was selected for activating non flowing wells. Starting in 1979, wells were completed with dual strings equipped with side pocket mandrel so as to set gas-lift valves by wire-line techniques. For wells completed during the 1973 - 1979 period, different methods had to be implemented because no heavy work-over ie - replacing dual tubing - had to take place. Alternative methods to flow the gas from the annulus to the string were selected :

Using a circulating device such as SSD already in the completion.

Punching a hole in the tubing wall and if necessary setting a 5/8" gas-lift valve between straddle pack off set by wire-line.

. Using a macaroni as an inner concentric completion set in place with a snubbing unit.

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